Co- and post-translational N-myristoylation is known to play a role in the correct subcellular localisation of specific proteins in eukaryotes. The enzyme that catalyses this reaction, N-myristoyltransferase (NMT), has been pharmacologically validated as a drug target in the African trypanosome, Trypanosoma brucei. Here we evaluate NMT as a potential drug target in Trypanosoma cruzi,the causative agent of Chagas disease, using chemical and genetic approaches. Replacement of both allelic copies of TcNMT was only possible in the presence of a constitutively expressed ectopic copy of the gene, indicating that this geneis essential for survival of T. cruzi epimastigotes. The pyrazole sulphonamide NMT inhibitor DDD85646 is 13- to -23-fold less potent against recombinant TcNMT than TbNMT, with Ki values of 12.7 and 22.8 nM, respectively, by scintillation proximity or coupled assay methods. DDD85646 also inhibits growth of T. cruzi epimastigotes (EC50 = 6.9 µM), but is ~1,000-fold less potent than that reported for T. brucei. On-target activity is demonstrated by shifts in cell potency in lines that over- and under-express NMT and by inhibition of intracellular N-myristoylation of several proteins in a dose-dependent manner. Collectively, our findings suggest that N-myristoylation is an essential and druggable target in T. cruzi.
21 Jan 2014